1. Field of the Invention
The present invention relates to a flexible disk apparatus which magnetically records information on and reproduces the recorded information from a recording surface of a flexible disk (widely employed under a trade name such as `Floppy Disk`), which is a disk encased in a jacket.
2. Description of the Prior Art
A typical conventional flexible disk apparatus has heretofore been arranged such that, with the disk kept rotating steadily, a magnetic head is brought into contact with the disk by a solenoid mechanism only when information is input or output (this operation will be referred to as "head loading", hereinafter). Since it is recent practice to rotate the disk by a DC motor with a short starting time, however, there is a growing tendency to employ a system wherein the solenoid mechanism for head loading is omitted, and, with the magnetic head always loaded on the disk, the disk is rotated only when information is recorded or reproduced. This system advantageously makes it possible to reduce the power consumption, weight and production cost of the flexible disk apparatus by virtue of the omission of the solenoid mechanism. Further, the system favorably prevents peeling off of the magnetic layer on the disk due to collision of the magnetic head with the disk surface in head loading and consequently permits the life of the disk to be prolonged. However, where the flexible disk apparatus is arranged such that head loading is effected by closing the door to the flexible disk insertion port, although it is possible to obtain the above-described advantages, the following two problems are caused when the door is closed without any flexible disk being inserted in the apparatus:
(1) The upper and lower magnetic heads may collide against each other and may be so damaged as to exert adverse effects on the recording and reproducing properties thereof.
(2) Since the surface of each magnetic head is ground so as to be extremely smooth, the upper and lower magnetic heads cohere with each other and are forcedly separated from each other when the door is subsequently opened. As a result, not only the magnetic heads but also gimbal springs supporting the same may be damaged, so that it becomes almost impossible to carry out normal recording and reproducing operations. In order to solve these problems, we have proposed a flexible disk apparatus in Japanese Utility Model Application No. 89,073/1983 which is provided with a head protecting mechanism adapted to prevent head loading when the apparatus has no flexible disk inserted therein regardless of whether the door is open or closed.
In the technical field of door mechanisms, on the other hand, in place of the conventional mechanism known as the "door-bridge system", a mechanism known as a "lever-cam system" has been proposed, as mentioned in, for example, Japanese Patent Publication No. 13,990/1983 (IBM). This lever-cam system mechanism is arranged such that the bore in the center of the flexible disk is clamped by means of a cam mechanism by pivoting a lever, which is pivotally disposed on the front side of the flexible disk apparatus, to the position where the lever closes a part of the flexible disk insertion port. This mechanism has the following advantages: The disk clamping state is easily made known from the position of the lever; the lever does not obstruct the disk loading and unloading operations and, therefore, the apparatus has excellent operability; and it is possible to cope with the need for a reduction in width of the apparatus without any structural difficulty.
The embodiment of the above-described Japanese Utility Model Application No. 89,073/1983 has the door mechanism which adopts the door-bridge system. FIG. 1, however, shows an example of the door mechanism in which the door-bridge system is replaced with the lever-cam system.
In the Figure, the reference numerals 1, 2 and 3 respectively denote a protection cam, a bail and a lifter. For the other constituent elements, the reader should refer to the embodiment of the present invention which will be described hereinafter.
Describing the operation of the example of the door mechanism shown in FIG. 1, when the flexible disk apparatus has no flexible disk inserted therein, the protection cam 1 restricts lowering of the bail 2 so as to hold magnetic head 21 in its unloaded state. When a flexible disk is inserted, the protection cam 1 is rotated so as to cancel the restriction of lowering the bail 2. When lever 11 is pivoted under this state, a cam 13 secured to the other end of a pivot 12 of the lever 11 pushes down an arm 14, thereby pushing down a clamp arm 24 engaged with the distal end of the arm 14. As the lifter 3 secured to the clamp arm 24 lowers, the bail 2 also lowers, thereby loading magnetic head 21. When the lever 11 is pivoted so as to return to its initial position, the lifter 3 pushes up the bail 2, thereby unloading the magnetic head 21. When the flexible disk is drawn out, the protection cam 1 rotates to return to its initial position where it restricts lowering of the bail 2 again, thereby holding the magnetic head 21 in its unloaded state.
This mechanism has no operational problem and, in particular, has the advantage that there is no portion which is subjected to excessive stress. The mechanism, however, requires a large number of elements which are exclusively used for protection, which involves a disadvantageously high production cost.
This problem of high production cost is substantially solved by arranging the flexible disk apparatus such that the lever is prevented from pivoting when the apparatus has no flexible disk inserted therein. This inhibition of lever pivoting may, however, cause damage to the head protecting mechanism unless the mechanism is arranged so as to adequately resist any force applied by an erroneous operation which would forcedly pivot the lever. On the other hand, if it is intended to realize the arrangement simply by increasing the rigidity of each element, the problem of high production cost arises again. In addition, it is difficult to house the head protecting mechanism in a flexible disk apparatus of narrow width without any obstruction.